Yahoo's free accounts cannot use POP3/IMAP.Yahoo's POP3 support is open only to paid users. POP3: Post Office Protocol v3, used to download e-mails. IMAP: Internal Mail Access Protocol, a replacement for POP3 with more advanced mailbox management functionality. HTTP: Web access... If you do want to use POP for your Yahoo account, you may check out YahooPOPs, which is a freeware local POP to HTTP proxy for your Yahoo! account.